The small FNR regulon of Neisseria gonorrhoeae: comparison with the larger Escherichia coli FNR regulon and interaction with the NarQ-NarP regulon

Table 3 P-box substitutions in E. coli NarQ.

Plasmid	Substitutions	P-box sequence	Phenotype
pBADEcQ	E. coli NarQ P-box	DAEAINIAGSLRMQSYRL	Nitrate and nitrite sensing
pRNW18	R54K	DAEAINIAGSLK MQSYRL	Ligand insensitive
pRNW19	N48E I49E	DAEAIEE AGSLRMQSYRL	Ligand insensitive
pRNW20	N48E I49E R54K	DAEAIEE AGSLK MQSYRL	Ligand insensitive
pRNW29	D43A E45S A46V N48E I49E	A ASV IEE AGSLRMQSYRL	Ligand insensitive
pRNW30	D43A E45S A46V	A ASV INIAGSLRMQSYRL	Ligand insensitive
pRNW31	D43A E45S A46V R54K	A ASV INIAGSLK MQSYRL	Ligand insensitive
pRNW32	D43A E45S A46V N48E I49E R54K	A ASV IEE AGSLK MQSYRL	Ligand insensitive
pRNW33	D43A E45S A46V S52N S57A	A ASV INIAGN LRMQA YRL	Ligand insensitive
pRNW34	D43A E45S A46V N48E I49E S52N R54K S57A	A ASV IEE AGN LK MQA YRL	Ligand insensitive

E. coli strains JCB391 (narXL narQ) or JCB12 (narXL narQ frdA::lacZ) transformed with pBADecQ expressing wild-type or mutated NarQ proteins were grown anaerobically in LB in the absence or presence of 20 mM NaNO₃ and the β-galactosidase activities determined. Mutations in the P box are shown in bold type. Wild-type NarQ was able to phosphorylate NarP in the presence of nitrate, activating expression of nirB and repressing frdA. Mutated NarQ proteins were inactive.

ISSN: 1471-2164